Hectograph blanket comprising a cellulose derivative gel and method of preparing andusing same



Feb. 3, 1942. w. J. CHAMPION 2,271,758

HECTOGRAPH BLANKET COMPRISING A CELLULOSE DERIVATIVE GEL AND- METHOD OFPREPARING ANDVUSING SAME Filed May 20, 1940 Patented Feb. 3, 1942HEOTOGR-AI'H BLANKET COMPRISING A CELLULOSE DERIVATIVE GEL AND METH- ODOF PREPARING AND USING SAME William .1. Champion, Berwyn, 111., assignorto Ditto, Incorporated, Chicago, 111., a corporation of West VirginiaApplication May 20, 1940, Serial No.336,226

19 Claims. (Cl. 41-313) H The invention relates to the art ofduplication and includes an improved hectograph blanket.

in the form of a pad or roll; also a method of preparing same, andmethod of duplicating therewith.

Heretofore hectograph blankets have been made from gelatinous massescomprising either glue or gelatin, or from acrylate resins as shown inUnited States Patent No. 2,153,324. The gelatin or glue masses have thedisadvantage of a certain amount of tackiness which has never beenentirely overcome. Further, they are sensitive to heat and humidity;they change their hardness and copying properties with time and requireextended aging periods before assuming their flnal properties. Theacrylate pads, while being free from many of these disadvantages,

are still excessively expensive dueto the high cost of ingredientsneeded for these rolls.

I have discovered that hectograph blankets of new and desirablecharacteristics can be made by forming the copy mass of a cellulosederivative gel whose liquid constituent is a relatively non-volatilesolvent for hectograph inks and, preferably present in substantiallylarger proportion than the cellulose derivative. The copy masses madefrom the cellulose derivative gels are characterized by a high degree oftoughness and by being especially repellent to paper and substantiallynon-tacky. Copies may be made therefrom according to the ordinaryhectograph procedure without moistening the surface of the copy mass.

Other objects and advantages of the invention will become apparent asthe following detailed description progresses, reference being had tothe accompanying drawing, in which Fig. l is a perspective view of ahectographroll embodying the invention; and

Fig. 2 is a section taken on line 22 of Flg. 1.

Referring to Figs. 1 and 2, in which the preferred embodiment of theinvention is shown. the reference character I designates a backing of aflexible strong sheet material such as cotton cloth covered on bothsides with a flexible zeinalcohol lacquer 2 and 3 and having a copy mass4 on the lacquer side 3, said copy mass consisting of a cellulose ethergel whose liquid constituent is a solvent for h'ectograph inks, whichboils at substantially above 100 0., and which is present in the gel insubstantially larger proportion than the cellulose ether. n

The cellulose derivative 'gel used for the copy mass of the hectographblanket is preferably a liquid similar to the ordinary gelatin or gluehectograph mass. However, the amount of liquid 1 may also be in minoramount, such as is present in ordinary plasticized cellular derivatives.vThe gel preferably is of the reversible type formed by cooling acolloidal solution. By the term cellulose'derlvative gel it is intendedto include colloidal solution of a liquid in a cellulose derivative, butit is not intended to include substances in which the liquid is merelyabsorbed by the cellulose derivative and can be entirely pressed out.Cellulose derivative gels which have been found to be suitable includenitro-cellulose gels,

cellulose acetate gels, and the various cellulose ether gels such asmethyl cellulose, ethyl cellulose, and benzyl cellulose gels.

The solid constituent of the gel suitably consists of a cellulosederivative such as cellulose nitrate, cellulose acetate, methylcellulose, ethyl cellulose, benzyl cellulose, and the like, either aloneor in admixture with each other or with other lyop'hilic colloids suchas gelatin or the acylate resins The preferred cellulose derivatives arethe cellulose ethers and the preferred cellulose ether is methylcellulose. q

The liquidconstituent of the gel is suitably a relatively non-volatiled'ye solvent and preferably a solvent-for water and alcohol soluble dyessuch as are used in ordinary hectograph inks. Suitably the liquid is asolvent for its cellulose derivative at an elevated temperature, and aplasticizer for the cellulose derivative at normal room temperature.Preferably the major proportion of the liquid should boll substantiallyabove C., and the liquid should be present in the gel in substantiallygreater proportion than the solid lyophilic colloid constituent of thegel. 1

The liquid may consist of a single'compound or mixture of compounds. Thecompound which is necessary to cause gelation from the sol state may ormay not be a solvent for hectograph inks (viz., benzyl alcohol), but ifit is not a solvent there is preferably admixed with it a solvent forhectograph inks so that the total liquid of the gel is a solvent.Furthermore, the total liquid of the gel is preferably a plasticizer forthe cellulose derivative, although the liquid may consist of aplasticizer and some a plasticizer admixed in such proportion that themixture itself is a plasticizer.

A suitable manner of preparing the gel is to choose. a. liquid(preferably a hectograph dye solvent) which is a solvent for asubstantial soft, tough gel containing a high proportion of 6:1 amountof cellulose derivative at anelevated temliquid which is not peratureand which will dissolve a substantially lesser quantity of the cellulosederivative at room temperature, then dissolve the cellulose derivativein this liquid at an elevated temperature to.

form a sol, and allow the sol to cool to room temperature, whereupon areversible gel forms. This procedure may be carried out by coating thehot sol on a flexible sheet such as cotton cloth or the like and thenallowing the sol to cool into a gel, thereby forming a hectographblanket comprising a backing having a copy mass of a cellulosederivative gel.

Thecellulose derivatives are generally dissolved in liquids boiling atabove 150 C. and are poured at a very high temperature, generally from130 to 140 C. as against 45 to 55 C. for gelatin and glue masses. Thecompositions therefore assume their final gel properties immediately oncooling without any aging period; they maintain their propertiesunchanged over very long periods of time, and they are practicallyindependent of the surrounding temperature.

Other methods of forming a cellulose derivative gel may be used, as forexample, the addition of a non-solvent for the cellulose derivative tothe sol, or the evaporation of the liquid compound causing solution froma mixture of compounds which together give a solvent for the cellulosederivative. Such procedures in general are not considered assatisfactory for the production of a hectograph blanket as the coolingmethod.

In making the hectograph blankets, the cellulose derivative sols may bepoured directly on a .fiexible backing sheet such as cotton cloth, paperor the like, and then gelled. However, preferably and particularly whenthe blanket is used as a roll, the backing sheet should havefaprotective coating on both sides. In such cases the cellulose derivativesolis coated and gelled on one side of the protective coating. Thisprotective coating may be any lacquer which is not'dissolved by thesolvent of the cellulose derivative which is poured thereon. A suitablelacquer consists of a solution of 20% zein and 80% of 80% ethyl alcohol.Good adhesion of the cellulose derivative gel to this dried lacquer isobtained when cellulose derivative sol is poured' over it and gelled.The zein lacquer has the further advantage that it is relativelynon-adherent to the cold cellulose derivative gel so that the blanketsin the form of hectograph rolls may be readily wound and unwound. It isnot necessary to have an intermediate bonding layer between theprotective lacquer of the backing and the cellulose derivative gel, butan intermediate bonding layer may be used if desired, and in some casesis advantageous. When a cellulose ether gel is used and the backing ofthe hectograph blanket is protected by a nitrocellulose lacquer, asuitable intermediate bonding layer consists of a composition ofcellulose ether containing a plasticiser which is in part or to someslight extent a sol.- vent for nitrocellulose. I-

To more clearly set forth the practice in accordance withthe inventionand to more specifically point out the nature of the product and processcontemplated thereby,'several specific, il-

- lustrative'examples are hereinafter set forth, it

being understood that these examples illustrate several embodimentswhich have given satisfactory results and are not intended restrict theinvention thereto.

Example I 200 grams of propylene glycol were heated. to l. grams ofmethyl cellulose of the high viscosity type were added with agitation.The resulting composition was poured onto cloth covered with anitrocellulose lacquer. and was allowed to cool about two minutes. Thismass is immediately ready for use. A test master was immediately appliedto the mass and good copies were taken oil in the-usual manner. The masswas unusually hard and firm, showed fair bond to the lacquer withouttheuse of special bonding agents and was exceptionally repellent to paper.

Example II 100 parts by weight of butyl phthalyl butyl glycollate wereheated to 130 C. 10 parts by weight of methyl cellulose of 1500centipoises viscosity If methyl cellulose of a lower viscosity is used,then a higher proportion of methyl cellulose should be used, and viceversa. The resulting sol was poured on to cloth covered with azein-alcohol lacquer and was allowed tocool. The hectograph blanket soformed is immediately ready for use. The copy mass had similarproperties to that of Example I and gave a similar number of goodcopies.

Example III cyclic acetal having a flash point of 75 0., speciflcgravity 1.074, refractive index 1.474,.and boiling point of 250 C. 30grams of ethyl cellulose was added to the 70 parts of Cyclonol withagitation to form a hot sol. The sol was then poured on to cloth coveredwith nitroceflulose lacquer and was allowed to cool, whereupon an ethylcellulose gel was formed on the backing. The hectograph blanket soproduced is immediately ready for use and gave a large number of goodcopies. I

1 Example IV A sol of the following composition was made by heating themixture with agitation to 160 Parts byweight Ethylene gly s Di-ethyleneglycol 6 Low viscosity cellulose acetate (Eastman,

Tenn., type E-2'l) 1 The hot solution formed of the above mixture wasthen poured on a backingand allowed to gel, forming a hectographvblanket having a copy mass of a cellulose acetate gel. Copies could beobtained from this hectograph blanketby the usual hectosraph process.

qlm p e V The following composition was mixed together to form a sol orcolloidal solution:

Percent by weight Ethyl aceta One-half second nitrocellulose 10 Carbitol(di-ethylene glycol mono-ethyl ether) 10 The solution so formed was thenpoured on a flexible backing and the ethyl acetate evaporated. This gavea hectograph blanket having a copy mass of what broadly'sp'eaking may becalled a cellulose nitrate gel. Gels having such a low proportion ofliquid as in this example are generally not preferred. However, where acopy mass is desired which is thinner than the copy mass of an ordinaryglue or gelatin hectograph blanket, the cellulose derivative compositionof the above example gave satisfactory results.

the design.

. from a copy sheet.

The hectograph blankets of this invention may be used in the same manneras ordinary gelatin.

' cellulose ether and a relatively non-volatile liquid the copy mass,each sheet receiving a proportion of the dye or coloring matter to forma copy of While it is in general herent in the invention as broadly aspossible, in

view of the prior art. I claim:

1. A hectograph blanket having a copy mass v desirable to use anordinary hectograph ink which comprises a water of a cellulosederivative hydrophilic gel whose liquid portion consists of a solventfor a water and alcohol soluble dye adapted to be transferred 2. Ahectograph blanket having a copy mass of a cellulose derivative gelwhose liquid p rtion consists of a solvent for a water and alcoholsoluble dye, said gel having the characteristic of being non-tacky andmore repellent to paper than ordinary gelatin hectograph gels.

3. 'A hectograph blanket having a copy mass of a gel comprising acolloidal solution of a-relatively non-volatile liquid in a cellulosederivative, said liquid comprising a solvent for water and alcoholsoluble dye anda plasticizer for the cellulose derivative.

4. A hectograph blanket having a copy mass of a cellulose derivative gelwhose liquid portion is a solvent for hectograph ink comprising waterand alcohol soluble dye, and is present in substantially greaterproportion than the cellulose derivative.

5. A hectograph blanket having a copy mass of a cellulose etherhydrophilic gel whose liquid portion consists of a solvent for a waterand alcohol soluble transfer dye.

6. A hectograph blanket having a copy mass of a gel comprising acolloidal solution of a relatively non-volatile liquid in a celluloseether, said liquid comprising a solvent for water and alcohol solubledye and a plasticizer for the cellulose ether. a

7,. A hectograph blanket having a copy mass of a cellulose ether gelwhose liquid portion is a solvent for hectograph ink comprising waterand alcohol soluble dye, and is present in substantially dissolving asubstantial amount of cellulose derivative at normal room temperature,said liquid being present in greater proportion than said cellulosederivative.

9. A hectograph blanket having a copy mass of a cellulose ether heatreversible gel comprising which is capable of dissolving a. substantialamount ot'the cellulose ether at above normal room temperature butincapable of dissolving a substantial amount of cellulose ether atnormal room temperature, said liquid being present in greater proportionthan said cellulose ether.

10. 'A hectograph blanket having a copy mass of a methyl celluloseheatreversible gel comprising methyl cellulose and a relativelynon-volatile liquid which is capable of dissolving a substantial amount01' the methyl cellulose at above normal room temperature but incapableof dissolving a substantial amount of methyl cellulose at normal roomtemperature, said liquid being present in greater proportion than insaid methyl cellulose.

11. A hectograph blanket having a copy mass of an ethyl cellulose heatreversible gel comprising ethyl cellulose and a relatively non-volatileliquid which is capable of dissolving a substantial amount of the ethylcellulose at above normal room temperature but incapable of dissolving asubstantial amount of ethyl cellulose at normal room temperature, saidliquid being present in greater proportion than said ethyl cellulose.

12. A hectograph blanket having a copy mass of a benzyl cellulose heatreversible gel comprising benzyl cellulose and a relatively non-volatileliquid which is capable of dissolving ,a substantial amount of thebenzyl celulose at'above normal room temperature but incapableofdissolving a substantial amount of benzyl 'cellulose at normal roomtemperature, saidliquid being present in greater proportion than saidbenzyl cellulose.

13. A hectograph blanket comprising a backing, a copy mass onone side ofthe backing comprising a cellulose derivative heat reversible gel, theliquid portion of which consists of a solvent for a transfer dye, and aprotective coating on lose derivative gel when pressed against the gelat normal room temperature.

15. The method of making a hectograph blanket, which comprises applyinga cellulose derivative sol comprising a cellulose derivative dispersedin'a liquid which is a solvent for water and alcohol soluble dye to abacking, and gelling the cellulose derivative sol.

16. The method of making a hectograph blanket which comprises forming asolution of a predetermined amount of cellulose derivative at anelevated temperature in a liquid which is capable of dissolving all ofthe cellulose derivative at'an elevated temperature but incapable ofdissolving all of said cellulose derivative at normal.

room temperature, coating the hot solution on a backing, and coolingsaid solution to room temperature to form a gel.

1'7. The method of making a. hectograph blanket which comprises forminga solution oi a predetermined amount of cellulose ether at an elevatedtemperature in a liquid which is capable of dissolving all oi thecellulose ether at an elevated temperature but incapable of dissolvingall tacting said design on the cellulose derivative gel with copy sheetsto reproduce the design on the copy sheets in positive.

19. A process of reproducing copies which comprises contacting the faceof a copy sheet having a design oi a soluble dye with a copy mass of a Icellulose ether gel whose liquid portion is a solvent tor the dye on thecopy sheet whereupon thedesimonthecopyshectistransierredin reverse tothe cellulose ether gel, and contacting said design on the cellulosederivative gel with copy sheets to reproduce the design on the copysheets in positive. v e s WILLIAM l. cnmlox.

